End sealing structure for heat pipe

ABSTRACT

An end sealing structure for heat pipe includes a sealed conical end formed at an end of the heat pipe, which is formed from a hollow metal pipe having a dead end opposite to the sealed conical end. The conical end is sealed at an outmost end thereof by more than one layer of weld bond, and coated with more than one layer of tin solder to enclose the weld bonds and the conical end, enabling the sealed conical end to keep an absolutely sealed state even the heat pipe is compressed in fabricating or under high internal pressure in a heated state. The heat pipe with the sealed conical end can therefore provide good heat-transport capability in a computer or any other apparatus that generates heat during operation thereof.

FIELD OF THE INVENTION

The present invention relates to an end sealing structure for heat pipe, and more particularly to an end sealing structure for heat pipe that effectively protects the heat pipe from the risk of leaking and therefore enables the heat pipe to provide good heat-radiating function.

BACKGROUND OF THE INVENTION

When a computer is operating, the high-power chip therein is often subjected to a heat accumulation effect and fails to operate normally. To protect the high-power chip against damage due to overheating, various types of radiating elements, such as cooling fans, radiating fins, heat pipes, etc., are developed for mounting in the computer to carry away heat produced by the high-power chip during operation thereof. The heat pipe has been proven to have a good heat delivering effect, and is gradually accepted by the computer industry. The high heat transport capability of the heat pipe has also been utilized in the automobile industry, the heat-interference prevention application in national defense, the recycling of residual heat in the energy and environment engineering, etc.

FIG. 8 shows a conventional heat pipe made of a hollow metal pipe 20, an end of which is a dead end 21, and the other end of which is a sealed end 23 with a weld bond 24.

Please refer to FIG. 7. To produce the conventional heat pipe of FIG. 8, first prepare a hollow metal pipe 20 having a predetermined length. An end of the hollow metal pipe 20 is shrunk and welded to form the dead end 21. Then, the pipe 20 is vacuumized, and a heat conducting liquid is filled into the vacuumized pipe 20. Thereafter, the other end of the pipe 20 is riveted to form a sealed U-shaped end 22.

The sealed U-shaped end 22 of the pipe 20 is then welded to form a weld bond 24 at an outmost end 23 of the U-shaped end 22 to complete a heat pipe.

Before the completed heat pipe can be used, it is normally subjected to a burst test for testing its sealing effectiveness. In the burst test, the completed heat pipe is positioned in a heating oven and heated, so that the heat conducting liquid in the sealed heat pipe is heated and finally vaporized. In the event the welded outmost end 23 may fail to bear the internal pressure of the heated heat pipe, the vapor of the heat conducting liquid would leak from the welded outmost end 23, proving the heat pipe is not reliable for use and forms a confusion to the manufacturer and the user.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide an improved end sealing structure for heat pipe, so that the heat pipe is more reliable for use without the risk of leaking and having poor transport capability.

To achieve the above and other objects, the end sealing structure for heat pipe according to the present invention includes a sealed conical end formed at an end of the heat pipe, which is formed from a hollow metal pipe and has a dead end opposite to the sealed conical end. The conical end has an outer diameter smaller than that of the metal pipe, and is sealed at an outmost end thereof by more than one layer of weld bond, and coated with more than one layer of tin solder to enclose the weld bonds and the conical end.

When the heat pipe with the sealed conical end is subjected to burst test or is in practical use, it is found the conical end is absolutely sealed by the two or more layers of weld bonds and tin solder without any leaking. Therefore, the heat pipe installed in a computer or used in any other suitable application field is able to stably and effectively provide a heat-delivery function without the risk of leaking at the sealed end.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

FIG. 1 is a perspective view of a heat pipe before being sealed at a U-shaped end according to the present invention;

FIG. 2 shows the heat pipe of FIG. 1 is primarily sealed at the U-shaped end by welding the end;

FIG. 3 shows the heat pipe of FIG. 2 is further processed at the primarily welded U-shaped end to form an approximately conical end;

FIG. 4 shows the conical end of the heat pipe of FIG. 3 is welded for a second time;

FIG. 5 shows the heat pipe of FIG. 4 is further coated with tin solder at the welded conical end to complete a heat pipe having an end sealing structure of the present invention;

FIG. 6 is a fragmentary and enlarged sectional view of the heat pipe of FIG. 5 showing the end sealing structure of the present invention;

FIG. 7 is a perspective view of a conventional heat pipe having a primarily sealed U-shaped end; and

FIG. 8 shows the heat pipe of FIG. 7 is further welded at the primarily sealed U-shaped end to complete the conventional heat pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 5 that is a perspective view of a heat pipe with an end sealing structure according to the present invention, and to FIG. 6 that is a fragmentary and enlarged sectional view of FIG. 5 showing the end sealing structure of the present invention. As shown in FIG. 5, the heat pipe is formed from a hollow metal pipe 10 having a dead end 11 and a sealed conical end 15 opposite to the dead end 11. The sealed conical end 15 has an outer diameter small than that of the hollow metal pipe 10, and is welded at an outmost end to form more than one layer of weld bond 14, 16. Follow by coated with one or more layers of tin solder 17 to enclose the weld bonds 14, 16 and the conical end 15.

Please refer to FIG. 1 that shows the metal pipe 10 before being processed to form the conical end 15. As shown, the metal pipe 10 has a predetermined length and two open ends. One of the two open ends of the metal pipe 10 is shrunk, spot welded, or welded to form a dead end 11. Since this is a known technique that can be easily accomplished by a person skilled in the art, it is not described in details herein. Then, the hollow metal pipe 10 is vacuumized, and a heat conducting liquid is filled into the vacuumized metal pipe 10. This is also a known skill and is therefore not described in details herein. Thereafter, the other end of the metal pipe 10 is tightly pressed and riveted to form a closed U-shaped end 12.

Please refer to FIG. 2. The closed U-shaped end 12 is welded or spot-welded at an outmost end to form a primarily sealed outer end 13 having a weld bond 14 located thereat.

Please refer to FIG. 3. Since the primarily sealed outer end 13 is formed by spot welding at high temperature, the weld bond 14 at the primarily sealed outer end 13 tends to become an arcuate body 141 due to a heat accumulation effect. Since the arcuate body 141 has relatively low structural strength at its peripheral areas, the closed U-shaped end 12 tends to leak due to deformation in the course of fabrication of the metal pipe 10, collision in the course of transport, or high internal pressure produced by the gasified liquid inside the metal pipe 10. Therefore, the closed U-shaped end 12 is further tightly pressed, riveted, and rounded to form a sealed approximately conical end 15 having an outer diameter smaller than that of the metal pipe 10.

Please refer to FIG. 4. The sealed conical end 15 is welded or spot-welded for a second time, so that a further layer of weld bond 16 is formed at an outmost end of the sealed conical end 15.

As having been mentioned earlier and shown in FIGS. 5 and 6, the sealed conical end 15 having the weld bonds 14, 16, which is coated with one or more layers of tin solder 17 to complete the heat pipe.

When the heat pipe with the conical end 15 welded twice or more times and coated with more than one layer of tin solder 17 is subjected to burst test or is in practical use, it is found the conical end 15 is absolutely sealed by the two or more layers of weld bonds 14, 16 and tin solder 17 without leaking, even when the heat pipe has a relatively high internal pressure or collides with something in the course of installation thereof. Therefore, the heat pipe installed in a computer, a car, or an interference prevention instrument is able to stably and effectively provide a heat-delivery function without the risk of leaking at the sealed conical end 15. 

1. An end sealing structure for heat pipe, said heat pipe being formed from a hollow metal pipe having a first end that is a dead end and a second end opposite to said first end, said end sealing structure comprising a sealed conical end formed at said second end of said metal pipe, said sealed conical end having an outer diameter smaller than that of said metal pipe and having more than one layer of weld bonds at an outmost end thereof.
 2. The end sealing structure for heat pipe as claimed in claim 1, wherein said sealed conical end has two layers of weld bonds at the outmost end thereof.
 3. The end sealing structure for heat pipe as claimed in claim 1, wherein said sealed conical end has more than two layers of weld bonds at the outmost end thereof.
 4. The end sealing structure for heat pipe as claimed in claim 2, wherein said sealed conical end is coated with one layer of tin solder to enclose said weld bonds and said conical end.
 5. The end sealing structure for heat pipe as claimed in claim 3, wherein said sealed conical end is coated with one layer of tin solder to enclose said weld bonds and said conical end.
 6. The end sealing structure for heat pipe as claimed in claim 2, wherein said sealed conical end is coated with more than one layer of tin solder to enclose said weld bonds and said conical end.
 7. The end sealing structure for heat pipe as claimed in claim 3, wherein said sealed conical end is coated with more than one layer of tin solder to enclose said weld bonds and said conical end. 